Study On Mechanical Behavior Of Assembled Concrete Beam-to-column Connections And Seismic Performances Of Frame Structure

Prefabricated structure has the advantages of good component quality,convenient construction,energy saving and environmental protection,which can well meet the green development requirements of modern construction industry.In order to ensure the overall performance and seismic performance of prefabricated structure,the prefabricated components must be connected by reliable joint.In this paper,the end plate connection is proposed,which come from end-plate connections of steel frame joints,uses high-strength bolts to connect the end plate components,precast beams and precast columns together to form a semi-rigid connection node and frame structure.In this paper,quasi-static test,theoretical analysis and numerical simulation are used to study the connection mechanism and seismic performance of semi-rigid joints.The calculation method of moment-rotation curve of the end plate connection joints is proposed,and the design method of semi-rigid connection frame is derived.The static elastic-plastic analysis of semi-rigid connection frame is carried out.The main contents are as follows:(1)Three semi-rigid end plate connection joints and one cast-in-place joint are designed,and the quasi static test is carried out.The deformation,failure mechanism and seismic performance index are studied.The experimental results showed that :when the rotational stiffness of the joint increases,local compression failure of the concrete occurs;when the end plate connection stiffness decreases,the end plate yield failure occurs;By welding the longitudinal reinforcement in the beam and the end plate firmly,the ductility and energy dissipation capacity of the joint can be improved through the coordinated deformation of the precast concrete beam and the end plate connector.(2)The finite element method is used to analyze the parameters of end plate connections,The effects of thickness of the end plate 、bolt diameter、 bolt vertical spacing and stiffener setting on on the mechanical performance of the joint are analyzed.The results show that the thickness of the end plate and the setting of stiffeners have great influence on the rotational stiffness and bending capacity of the joint.Too small bolt diameter will make the joint failure due to premature yield of the bolt,and the bolt spacing has little effect on the mechanical performance of the joint.(3)Through theoretical analysis,a reasonable calculation method of moment rotation curve of of the end plate connection joints is obtained.(4)A design method of prefabricated concrete frame with end plate connection is summarized.Based on this method,a frame is designed and pushover analysis is carried out.The results shows that the plastic hinge is formed by the end plate yielding and the column base failure when the end plate connection prefabricated concrete frame structure is damaged,which has reasonable energy dissipation mechanism and good anti overturning ability,and the elastic deformation and elastic-plastic deformation of the structure meet the requirements.